This invention relates to a pressure control device adapted for regulating the flow of a fluid medium and having fluid inlet conduit means, fluid return conduit means and a connecting means for link-up with a fluid consuming device, as well as a movable valve member which controls the cross sectional area of the fluid outlet; this device is particularly adapted for the regulation of the control fluid of a fuel metering device for internal combustion engines.
Such pressure control devices are required to regulate very rapidly, but also to afford a high quality, i.e., very accurate regulation even at small pressure differences. Moreover, they should be capable of regulating pressures down to zero. In the known control devices initially described the fluid inlet conduit means comprise a throttle, and the pressure on the side of the consuming device is regulated by a control of the fluid outflow cross sectional area. These known systems suffer from the drawback of having a continuous outflow of oil at smallest and medium pressures; furthermore, they do not permit regulation of the pressure in the return conduit means down to zero, since, in order to permit this, no resistance at all should occur in the return conduit. Moreover, the regulating time required for such devices is relatively long, as there must be maintained a continuous influx of liquid via the fluid inlet conduit means.